While the fast-food industry is in the news because of worker strikes, the restaurant companies with the most employees optimistic about the future of their company are busy growing and keeping their employees happy.

Job site Glassdoor pulled together some information for The Motley Fool based on employee business-outlook ratings posted between May 25 and Aug. 24 in response to the question "In the next six months, do you believe your company's business will perform better, stay the same, or get worse?" A fast-food company, Chick-Fil-A, tops the list but most of the rest are fast-casual and full-service chains.

Sunnier than average employee outlooks

What's striking about the results is how much more optimistic these companies' workers are than the work force in general, according to information submitted to Glassdoor. Sixty-three percent of Chick-fil-A's employees who submitted reviews on Glassdoor believed their business would improve over the next six months. That makes sense based on the privately held company's strong growth record. Chick-Fil-A recorded sales of $5 billion in 2013, up from $4.6 billion in 2012 and $4.1 billion in 2011. There are 23 new store openings scheduled through the end of 2014.

Sixty percent of Chipotle Mexican Grill (NYSE:CMG) workers who left reviews felt the same way about their company's prospects, and 56% of Starbucks (NASDAQ:SBUX) employee reviewers shared similar sentiments. 

"For reference, among 300,000 companies on Glassdoor, the average business outlook rating for employees who believe business is getting better is 37%," said MaryJo Fitzgerald, Glassdoor senior public relations associate, in an email. The current business outlook numbers given by employees of beleaguered burger chains are lower than average: 35% for workers at McDonald's (NYSE:MCD), 32% at Wendy's (NASDAQ:WEN), and just 27% among Burger King Worldwide's (UNKNOWN:BKW.DL) employees.

How are the restaurant companies with the best business outlooks in this Glassdoor survey generating confidence in their work force? As with list leader Chick-Fil-A, solid performance and expansion plans seem to be key ingredients.

Chipotle's growth offers workers stability, opportunity, and a brand halo

Chipotle has a cool factor that's hard to beat: a customizable menu, an emphasis on local produce, and marketing that's as much about eating well as it is about eating at Chipotle. Those things make Chipotle desirable to consumers and workers, too. Given a choice between working for former Chipotle owner McDonald's or working for a company with a healthy-living halo, most workers would choose the latter.

Besides a feel-good vibe for employees, the company's addition of new stores and record of strong comparable-store sales means more opportunities for work hours and advancement. In fact, in some places the company may not be hiring fast enough. College students working at the Penn State location walked off the job this week, citing short-staffing and overwork. The store has since reopened.

Overall, though, Chipotle employees who left Glassdoor reviews seemed upbeat, and they're not the only ones. Analyst Mark Kalinowski at Janney's made waves this week when he forecast that if the company's growth continues apace, the stock price could rise as high as $1,500 by the end of 2020. Given Chipotle's popularity with customers and investors and the company's growth plans, workers have solid reasons for their optimism.

Starbucks gets creative with expansion plans

Starbucks has a simple range of items -- coffee drinks, teas, sandwiches, and baked goods -- but the company's not letting its store setups get stale. Starbucks is preparing to test new store formats that will specialize in hard-to-find coffees and offer faster counter service with mobile payments. Those new stores should give current employees more opportunities to advance within the company.

While Starbucks isn't the media darling Chipotle is, it's outperforming the restaurant industry, with higher than average revenue, net income, and cash flow growth and a below average debt-to-equity ratio. Again, brand popularity, financial analysis, and growth plans back up employees' expectations for the company.

Optimistic workers are one corner of the "3 P" triangle

When a successful company has mostly optimistic workers, the combination creates a positive feedback loop that's its own kind of asset to the company. Followers of entrepreneur and TV host Marcus Lemonis are familiar with his 3 P philosophy, inherited from his mentor Lee Iacocca: people, process, and product.

Lemonis believes that strong businesses are based on people who are effective rather than destructive -- and few things are more destructive than the contagion of a bad attitude. Effective people, the thinking goes, can work any properly structured process to deliver a desirable product, yielding a fourth P, profit.

It's probably not coincidental that the only three restaurant chains on Glassdoor's list of the 50 best big companies to work for in 2014 are also among the top 10 for business outlook this season: Chick-fil-A, Starbucks, and Texas Roadhouse (NASDAQ:TXRH). And on Glassdoor's new list of the top 10 companies with career opportunities for high school graduates, Chipotle and Starbucks are the only restaurant chains.

Employee moods aren't financial numbers, and it's impossible to quantify the value of an optimistic workforce. Still, fired-up employees are a signal that a company is doing something right and should continue to do so over the next few months.

Casey Kelly Barton has no position in any stocks mentioned. The Motley Fool recommends Burger King Worldwide, Chipotle Mexican Grill, McDonald's, Starbucks, and Texas Roadhouse and owns shares of Chipotle Mexican Grill and Starbucks. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.